In the production of disposable glass syringes for receiving liquid drugs, it is common to apply a high viscosity liquid silicone material or oil on the inner surface of the syringe barrel to minimize friction for the piston mounted on the syringe plunger and to maintain a positive fluid-tight seal between the piston and the glass barrel of the syringe. In order to apply an evenly dispersed uniform coating of the silicone oil over the inner surface of the barrel, it is desirable to atomize the liquid into microscopic droplets with minimum air pressure, for example, less than 15 psi to avoid blowing the atomized liquid from the barrel. It is also desirable to provide for rapidly and precisely pulsating the atomized liquid, for example, on the order of several pulses per second, in order to coat a large volume or flow rate of syringes and to avoid the liquid dripping from the spray nozzle.